Kashikoi ko
"Wise one" in Japanese is erai hito.偉い人
kashikoi inu
Japanese just use kodomo as in child
"tsuki komodo"
the world child? you can say SEKAINO KODOMO(TACHI).
'black haired child' is "KuroKami No Kodomo"
You may say 'nakuko.'
Karate is a Japanese world, so it would be said the same way. The Japanese word for child is kodomo.
Kashikoi
Literally, you may say 'kage no ko,' written: 影の子
Okami Ko?. It means "wolf child" I think. If not, sorry.
The translation is "Ko" yes, Child in Japanese is "Ko"